Gravity davit construction



Dec. 20, 1960 w. F. HICKSON GRAVITY DAVIT CONSTRUCTION 4 Sheets-Sheet 1' Filed Jan 5, 1956 INVENTOR M'Zliam [Egg/Q ATTORNEY Dec. 20, 1960 w. F. HICKSON GRAVITY DAVIT CONSTRUCTION 4 Sheets-Sheet 2 Filed Jan. 3, 1956 Dec. 20, 1960 w; F. HICKSON GRAVITY DAVIT CONSTRUCTION Filed Jan. 5, 1956 4 Sheets-Sheet 3 I INV-ENTOR MZlz'am Ff] ATTO R lll Dec. 20, 1960 w. F. HICKSON GRAVITY DAVIT CONSTRUCTION Filed Jan. 3, 19 56 4 Sheets-Sheet 4 ATTORNEY United States Patent GRAVITY DAVIT CONSTRUCTION William F. Hickson, Clark Township. Union County, N.J., assignor to Continental Copper & Stee Industries, Inc., New York, N.Y., a corporation of Delaware Filed Jan. 3, 1956, Ser. No. 557,029

13 Claims. (Cl. 9-38) The present invention relates to a davit construction and particularly relates to a gravity davit construction.

It is among the objects of the present invention to provide a gravity davit construction which may be readily installed, and wh ch will reliablv launch a lifeboat with maximum balancing and with assurance that there will be no banging or rocking during the launching procedure.

Another object is to provide a novel gravity lifeboat davit construction in which the davit will make most use of available boat stowage space and will have satis: factory lifting and launching speeds and will be capable of launching a lifeboat under a wide variety of conditions or lists of the ship on which the davits are mounted.

A particular object of the present invention is to provide a linked gravity davit construction which will reliably launch a lifeboat from an elevated position of stowage upon the deck of a ship and which will not tend to jam or require special motors or winches during the launching or lifting procedures.

Still further objects and advantages will appear in the more detailed description set forth below, it being understood, however, that this more detailed description is given by way of illustration and explanation only and not by way of limitation, since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In accomplishing the objects according to one preferred form of the present invention, the davit is provided with a double linkage construction in which the main arm of the davit will be carried by a plurality of links mounted upon the base deck or ship structure.

In the preferred form of the invention the main davit arm or structure is mounted upon a link which in turn is mounted upon the other links which will permit the arm either to be retracted in elevated position for boat stowage or moved outwardly substantially away from the side of the ship for launching purposes.

With the foregoing and other objects in view, the invention consists of the novel construction, combination and arrangement of parts as hereinafter more specifically described, and illustrated in the accompanying drawings, wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications can be resorted to which fall within the scope of the claims hereunto appended.

In the drawings wherein like reference characters denote corresponding parts throughout the several views: Figure 1 is a top plan view showing one form of davit construction according to the present invention with the winch in position.

Figure 2 is a front elevational view showing the mounting of the davit arms and associated structures on the side of a ship.

Figure 3 is an end elevational view showing the linkage structure associated with the davit.

Figure 4 is a diagrammatic layout showing the position Referring to Figs. 1 to 4, there is shown the davit structure A with which is associated the tapered drum winch structure B and the whale boat or lifeboat C.

The davits, as shown in Fig. 2, have the intermediate supporting structure D and standards E.

Referring to Figs. 3 and 4 there are provided the main upstanding davit arms F which are carried by the main transverse arm G.

The ends of the support arm G are carried by the inboard link H and the outboard link I. These links are in turn mounted upon the structural members K and L.

Referring to Figs. 1 to 3 other cables 10 and 11 extend from the winch B over the pulleys or sheaves 12, 13 and 14.

From the sheaves or pulleys 12 and 14 at the rear base portion of the d vit construction the cables then extend over the pullevs 15 and 16 carried by the structural member 17 and thence forwardly to the pulleys 18 and 19 at the top of the davits.

From the pulleys 18 and 19 the cables will extend around the pulleys 28 which are held in the U-shaped clips 29 suspended from the top ortions 30 of the main davit arms F. From the clips 29 there extend the rods or eye bars 31 which are connected at 32 to the whale boat or lifeboat C.

From the pulleys 28 the cables will extend to the pulleys or sheaves 20 and 21 which are connected to the cables 22 and 23 whi h extend rearwardly to the sheaves or pulleys 24 and 25 and terminate in the take-up members 26 and 27. The take-up members 26 and 27 are mounted upon the base of the davit structure as indicated at 33 and 34.

The davit arm F, itself, referring to Figure 4, has an upper outboard-turned portion 50 and a lower base portion 51. The lower base portion 51 is mounted upon the cross arm or transverse arm G. The base link G has an inboard pivotal connection 52 to the link H.

The link H in turn has an inboard pivotal connection 53 to the standard or structural member K which is mounted upon the ship structure as indicated at 53.

The outboard end of the arm G has a pivotal connection at 54 to the outboard link I. The link I at its fixed end is pivotally mounted at 55 upon the structure member L which consists of the lower beam 56 and the upper davit structure at 63 and the lower oblique beams 64 which are connected to the ship structure at 65.

Referring to Fig. 3, there is shown a side triangularframe structure which carries the coupling 76 connected' to the turnbuckle 77. From the turnbuckle 77' there extends the cable 78 which extends horizontally 'at: 79 and then downwardly at 80 to the mounting point 81..

The operation is best illustrated upon Figure 4. The various positions from 1 to 15 for the top 30 of the davit. arm F will correspond to the same positions of the pivot: point 52 of the link H and the pivot pin 54 of the link J. It will be noted that the main bar G is longer than the links H and J. In one preferred form the ratio of length of the bar G to the length of the links H and I will be in the order of 52 31 30.

However, this ratio may vary from 60 30 30 to 44 3O 30 depending upon the particular structure and weight of the boat and of the ship. Although the outboard link I should be approximately of the same length as the inboard link H, desirably it has been foundtliat the inboard link H should have a length of 5% 'to 10% more than the length of the outboard link I.

In the extreme inboard position the longitudinal center lines of the two links H and I should intersect at a point in front of the top of and slightly above the davit, as indicated at top point 15 shown at 100 in Fig. 4. At the extreme outboard position the two links should intersect at a point 101, which is substantially directly below and slightly inboard of the outer end of the davit, also designated as 05 in Fig. 4.

For each position indicated upon the circle 102 similar positions will be indicated in the circle 103 for the pivot 55 and the link I and in the circle 104 which corresponds to the outside pivot point 62 of the inboard link H. The intersection of the longitudinal axes of the links H and I will be indicated by the circle of numerals 105 on Fig. 4.

In this arrangement the davit at its extreme outboard position as indicated by the dot-and-dash lines in Fig. 4 will not come to an abrupt stop but will have a certain amount of give and the boat upon the davit will be gradually lowered without coming to an abrupt bang at the limit of outboard movement. This will give the launching of the boat a cushioning effect. The arrange ment as shown will give maximum balance and will provide an automatic stop and it will permit the boat, as well as the davit arm to move over the hump without requiring an excess of power. Moreover, the intersection of the two links H and I will always be inside of the davit arm and the rear link H will swing in a circle which will intersect the circle of the outboard link I. Both links will extend outwardly to give the maximum overboard throw when the davit is in its outboard position and both will extend inwardly into substantially parallel positions when the davit is in its maximum inboard position. This will give maximum safety to the boat launching and assure that there will be no inadvertent, abrupt stopping either at the maximum inboard position or at the maximum outboard position. As a result there is only a minimum power required from the davit motor and maximum safety assurance is obtained.

While there has been herein described a preferred form of the invention, it should be understood that the same may be altered in details and in relative arrangement of parts within the scope of the appended claims.

Having now particularly described and ascertained the nature of the invention, and in what manner the same is to be performed:

What is claimed is:

1. A gravity davit construction having a main swinging davit, a transverse supporting cross bar for said davit, and pivotal supporting links for each end of said cross bar, each link being pivotally connected at one end to said bar and mounted at its other end to the ship structure, the intersection point of the longitudinal axes of the pivotal supporting links being in front, slightly above and to the outboard of the upper outer end of the davit in extreme inboard position and substantially directly below and slightly inboard of the outer end of the davit in extreme outboard position.

2. A gravity davit construction having a main swinging davit, a transverse supporting cross bar for said davit, and pivotal supporting links for each end of said cross bar, each link being pivotally connected at one end to said bar and mounted at its other end to the ship structure, said cross bar having a length from one and onehalf to two and one-half times the length of said links and said links having approximately the same length, the intersection point of the longitudinal axes of the pivotal supporting links being in front, slightly above and to the outboard of the upper outer end of the davit in extreme inboard position and substantially directly below and slightly inboard of the outer end of the davit in extreme outboard position.

3. A gravity davit construction having a main swinging davit, a transverse supporting cross bar for said davit,

.- and pivotal supporting links for each end of said cross bar, each link being pivotally connected at one end to said bar and mounted at its other end to the ship structure, said links both extending convergently outwardly at the extreme outboard position of said davit and both extending convergently upwardly at the extreme inboard position of said davit, the intersection point of the longitudinal axes of the pivotal supporting links being in front, slightly above and to the outboard of the upper outer end of the davit in extreme inboard position and substantially directly below and slightly inboard of the outer end of the davit in extreme outboard position.

4. A gravity davit construction having a main swinging davit, a transverse supporting cross bar for said davit, and pivotal supporting links for each end of said cross bar, each link being pivotally connected at one end to said bar and mounted at its other end to the ship structure, said swinging davit approaching its extreme end positions without an abrupt stop, the intersection point of the longitudinal axes of the pivotal supporting links being in front, slightly above and to the outboard of the upper outer end of the davit in extreme inboard position and substantially directly below and slightly inboard of the outer end of the davit in extreme outboard position.

5. A doublelinked gravity davit construction of the type having a main davit arm with a withdrawn retracted position for boat stowage and outward boat launching position and with an extended base having an inboard end and an outboard end, and inboard and outboard links pivotally connected to the ends of said base, the length of the extended base being greater than the length of the individual links and the inboard link extending upwardly from its pivotal connection to the inboard end of the base in both withdrawn and launching positions and the inboard and outboard links being about equal in length and between /2 and /s the length of the extended base, the links and extended base cooperating in preventing an abrupt stop of the davit in movement to outboard position and providing a cushioning effect and permitting the davit arm to move over the hump without excess of power.

6. The davit of claim 5, said inboard link having a length of 5% to 10% more than the length of the outboard link and the ratio of the length of the base to the inboard link to the outboard link being about 52:31:30.

7. The davit of claim 5, the ratio of the inboard link to the outboard link to the extended base in length varying from 30:30:60 to 30:30:44.

8. The davit of claim 5, the longitudinal center lines of said inboard and outboard links intersecting at a point in front of the upper end of the davit at withdrawn position of the davit and intersecting at a point substantially below the outer ends of the davit and on the same level of the lowermost pivotal connection at the launching position and intermediate intersecting positions lying in a circular arc traversed by the upper end of the davit in its movement from stowage to launching position, the end of the outboard link pivotally connected to the outboard end of the extended base moving in an approximately parallel arcuate circular path.

9. A gravity davit construction comprising a davit arm having outboard and inboard positions and having spaced movable inboard and outboard pivot connections adjacent the base thereof, an inboard link pivotally connected to the inboard connection at one end, an outboard link pivotally connected to the outboard connection at one end, and a support structure having spaced fixed pivot mounts for said links at their other ends and the ward position directly below and slightly inboard of the outer end of the davit arm.

11. The construction of claim 9, the distances between the pivot connections of the inboard link, the outboard link, and the base of the davit being in the ratio of 31:30:52.

12. The construction of claim 9, in said inboard position, said inboard link extending downwardly obliquely inboard and said outboard link extending upwardly obliquely upboard from their fixed connections and in 10 outboard position both extending convergently therefrom obliquely downwardly outward.

13. The construction of claim 9, the distances between the pivot connections of the inboard link, the outboard link, and the base of the davit being in the ratio of between 30:30:60 and 30:30:44.

References Cited in the file of this patent UNITED STATES PATENTS 2,647,269 Cappel Aug. 4, 1953 2,705,332 Moore Apr. 5, 1955 FOREIGN PATENTS 159,241 Australia Oct. 8, 1954 

